Apparatus for aerohydrodynamic abrasive cleaning of surfaces, sprayer for the same, and method for aerohydrodynamic abrasive cleaning of surfaces

ABSTRACT

An apparatus for mechanical spray treatment of materials has a container for preparing an abrasive suspension, the container having a stirring mechanism including a stirrer provided with at least one blade, and a sprayer for spraying the abrasive suspension connected to the container and a compressed gas supply device. The stirrer of the stirring mechanism has a comminuting cutter provided thereon in the bottom part of the container. The method for aerohydrodynamic abrasive cleaning of surfaces includes entraining the abrasive suspension flow in compressed gas to produce aerosol particles and directing the stream of aerosol particles from the sprayer nozzle to a surface. Moreover, after aerosol particles have been formed they are accelerated owing to the sprayer design within the sprayer before they are ejected from the nozzle. The method and device help improve the output, efficiency, and quality of cleaning by improving the uniformity of abrasive material grains used and imparting a high velocity to the suspension spray, expanding the area of effective cleaning, and distributing the aerosol particles therein in an optimal proportion.

CROSS REFERENCE TO RELATED APPLICATIONS

Applicant claims priority under 35 U.S.C. §119 of Russian ApplicationNo. 2010110986 filed Mar. 23, 2010, the disclosure of which isincorporated by reference.

BACKGROUND OF THE INVENTION

The group of inventions relates to mechanical spray treatment ofmaterials and can be used in various fields for cleaning any surfacesfrom organic and inorganic dirt, removing coatings, including coatingremoval layer by layer; for imparting new adhesive properties to thesurface cleaned; combining surface cleaning and passivating; andcleaning many types of items meeting specific requirements to fatiguestrength and uncontrollable chemical processes in operation.

The invention can be used in the heavy and metal industries, forexample, on the shop floor of metal making plants for removing scalefrom the surface of semi-manufactured products made of ferrous andnonferrous metals; in blank production shops of mechanical engineeringplants for removing oxide films, rust, and so on; cleaning prior topainting; preparing surfaces for welding, brazing, and application ofcorrosion-resistant and other protective coats; dimensionless grindingpreceding final polishing of components; cleaning filled floors; and soon. In power engineering, the oil and gas industries, and aviation, theinvention can be used, for example, for cleaning and treating the bladesof turbine rotors at cogeneration plants, hydroelectric power plants,nuclear power plants (repairs of gas turbine and steam engines,turbines, and so on), and aircraft engines; cleaning and treating theblades of turbine rotors of oil and gas piping equipment; cleaningpipeline elements and threads; deactivating radioactive contamination,and so on. In transportation and at shipyards, the invention can be usedfor cleaning railroad cars from dirt, including graffiti, cleaningrailroad cars, wheel sets of railroad cars prior to flaw detectionprocedures; cleaning vehicle bodies and preparing components prior topainting; and cleaning ship hulls, components, and equipment. In housingand utilities, construction, and restoration projects, the invention canbe used for cleaning various house front surfaces from atmosphericpollutants, dirt and soil, artificial pollution, and biologicaldestructive agents.

The closest prior art of the claimed apparatus for aerohydrodynamic(AHD) abrasive cleaning of surface, its sprayers, and cleaning methodare, respectively, the apparatus, sprayer, and cleaning method disclosedin U.S. Pat. No. 1,740,142 A1 published on Jun. 15, 1992 [1].

The prior art apparatus for aerohydrodynamic abrasive cleaning ofsurfaces comprises a container for preparing an abrasive suspension,including a stirring mechanism provided with a bladed stirrer, and asprayer provided with a flaring nozzle to spray the abrasive suspensionand connected to the container and a compressed air device.

The prior art apparatus is disadvantageous because of the low quality ofcleaning by mixtures containing relatively coarse and/or nonuniformgrains.

The prior art sprayer for aerohydrodynamic abrasive cleaning of surfacescomprises a hollow body provided with a flaring nozzle at the outlet,and a compressed air flow channel and a cleaning suspension flowchannel, both connected to the body interior.

The prior art sprayer is disadvantageous because of its low cleaningefficiency due to improper matching of the suspension spray velocity,concentration of abrasive particles in the suspension, and the shape andeffective area of the cleaning flare.

The prior art method for aerohydrodynamic abrasive cleaning of surfacescomprises injecting compressed gas into the abrasive suspension flow toproduce aerosol particles and directing the stream of aerosol particlesfrom the sprayer nozzle at the surface being cleaned.

The prior art method is disadvantageous because of its low cleaningefficiency due to improper matching of the suspension spray velocity,concentration of abrasive particles in the suspension, and the shape andeffective area of the cleaning flare.

SUMMARY OF THE INVENTION

The technical result of the claimed group of inventions consists inincreasing output, efficiency, and quality of cleaning by improving theuniformity of abrasive material grains and imparting a high velocity tothe suspension spray, enlarging the effective cleaning area, andachieving optimal distribution of abrasive particles and water therein.

The technical result is achieved in an apparatus for aerohydrodynamicabrasive cleaning of surfaces, said apparatus comprising a container forpreparing abrasive suspension that has a stirring mechanism including astirrer having at least one blade, and a sprayer for spraying theabrasive suspension that is connected to said container and to acompressed gas supply device, said stirrer of the stirring mechanismcomprising a comminuting cutter provided thereon in the bottom part ofthe container.

In the specific embodiments of the invention, the stirring mechanism maycomprise an air motor connected to the stirrer and to the compressed gassupply device through an air preparation unit that includes a drier anda lubricant supply device.

The suspension preparation container may be provided with a fillingfunnel having a locking device.

The apparatus may be provided with a washing liquid container connectedto the sprayer through an air pump that is connected to the compressedair supply device through the air preparation unit including a drier anda lubricant supply device.

The apparatus units may be interconnected by hoses provided with valves,the hoses connected to the sprayer having pressure gauges.

The grain non-uniformity problem has been resolved by providing theapparatus with a comminuting cutter, a structural element that makes themass uniform and suitable for producing an AHD mixture and helps grindlarger grains to a particle size of 100 μm to 300 μm that are moreeffective in cleaning a larger area in square meters per hour.

The object of this invention is also achieved by the specific design ofa sprayer for aerohydrodynamic cleaning of surfaces that contains ahollow body provided with a nozzle at the outlet thereof, a compressedair flow channel and a cleaning suspension flow channel, both connectedto the body interior, the compressed air flow channel being connected tothe cylindrical interior of the body at the side opposite to the nozzle,the sprayer being provided with an atomizer in the shape of T pipeplaced within the body interior, the crosspiece of the T pipe extendingalong the body axis and the vertical leg thereof being connected to thecleaning suspension flow channel; the nozzle having a tapering part anda cylindrical part at the outlet thereof, and the outlet aperture of theatomizer being positioned at a distance from the inlet of thecylindrical part of the nozzle to provide a zone for accelerating theaerosol particles of the cleaning suspension.

The object of the invention is also achieved in a method foraerohydrodynamic abrasive cleaning of surfaces comprising injectingcompressed air into the abrasive suspension flow to produce aerosolparticles and directing the stream of aerosol particles from the sprayernozzle at the surface, the aerosol particles produced as above beingaccelerated within the sprayer before they are ejected from the nozzle.

It is preferred to use a nozzle having a part that does not flare at theoutlet thereof.

Furthermore, the abrasive suspension used for the purposes of thisinvention contains solid particles of loam and silica in water in thefollowing proportions of solids, in mass %:

loam 25 to 90

silica 10 to 75

It is preferred for loam and silica solids to have a size ranging from100 μm to 1.8 mm.

BRIEF DESCRIPTION OF THE DRAWINGS

The idea of the invention is described below with reference to thedrawings wherein;

FIG. 1 is a diagrammatic view of the claimed apparatus;

FIG. 2 is a view of a first embodiment of a through sprayer using a Tpipe; and

FIG. 3 is a diagram showing connections between the units of the claimedapparatus.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The apparatus for aerohydrodynamic abrasive cleaning of surfaces (see:FIG. 1 and FIG. 3) comprises a container 1 for preparing abrasivesuspension that includes a stirring mechanism and a sprayer 2 forspraying the abrasive suspension connected to container 1 and acompressed gas supply device 3.

The stirring mechanism comprises a stirrer 4 and an air motor 5associated therewith and connected to a compressed gas supply device 3through an air preparation unit 6 that includes a drier 7 and alubricant supply device 8. Stirrer 4 is provided with blades 9 and acomminuting cutter 10 provided thereon in the bottom part of container1.

Stirring container 1 is provided with a filling funnel 11 having alocking device 12.

The apparatus has a washing liquid container 13 connected to sprayer 2through an air pump 14 connected to compressed air supply device 3through air preparation unit 6.

The apparatus units are interconnected by hoses provided with valves 15,with pressure gauges 29 provided on the hoses connected to sprayer 2.The hose connecting air preparation unit 6 to container 1 is providedwith a pressure gauge 30.

The top part of container 1 is provided with a filling aperture 31 and a6 atm. safety valve 32.

Sprayer 2 (see: FIG. 2) comprises a hollow body and a nozzle 17 at theoutlet thereof. The interior of container 1 is connected to a compressedair flow channel and a cleaning suspension flow channel 19. Compressedair flow channel 18 is connected to the cylindrical interior of body 1at the side thereof opposite to nozzle 17. The interior of body 1 housesan atomizer in the form of a T pipe 20, the crosspiece 21 thereofextending along the body axis, and the vertical leg 21 thereof beingconnected to cleaning suspension flow channel 19′. Nozzle 17 has atapering part 23 and a cylindrical part 24 at the outlet thereof, theoutlet opening 25 of the atomizer being spaced at a distance from theinlet of cylindrical part 24 of nozzle 17 to provide an accelerationzone for the aerosol particles of the cleaning suspension.

Sprayer 2 has a clearly defined zone (Zone A) for accelerating theincoming air. It also has a Zone B for accelerating the mixture of airand cleaning suspension for mixing air with the suspension and initiallyaccelerating the resultant mixture, and a Zone C in nozzle 24 of theaccelerator for accelerating the mixture still further to produce aworking flare of a large area and high cleaning efficiency.

Examples of loam and quartz dust mixtures used for cleaning purposes:

PP-MT 30: 30% of loam and 70% of powdered quartz;

PP-MT 50: 50% of loam and 50% of powdered quartz;

PP-MT 70: 70% of loam and 30% of powdered quartz; and

PP-MT 90: 90% of loam and 10% of powdered quartz.

The cleaning mixtures are dispersions of washed loam and special-purposeadditives.

The above-mentioned mixtures may comprise GOST-28177-89 Standard loam ofgrain size down to 40 μm and GOST-9077-82 Standard powdered quartz ofgrain size down to 40 μm.

It is more preferred, though, to use grains ranging from 100 μm to 1.8mm in size. Coarser grains are used for removing heavy pollution such ascorrosion and aged paint and allow surfaces to be cleaned to quality Sa2under ISO 8501-1 Standards, and finer grains (between 100 μm and 300 μm)are further comminuted as they are mixed and are suitable for AHDcleaning and treating surfaces without modifying the chemicalcomposition of the surface layer thereof, which is a critical factor formany types of items required to have a high fatigue strength andresistance to uncontrolled chemical processes in operation, and achievecleaning quality of Sa3 under ISO 8501-1 Standards.

The choice of a cleaning mixture depends on the extent and type ofpollution of the surface to be cleaned, equipment, finishing materials,conditions of house front walls, and presence of architectural features,and is dictated by the technique adopted for a specific job.

A majority of pollutions are cleaned by a mixture of no more than 6liters of cleaning mixture and 40 liters of water. Tap water is used forultimately washing the cleaning products off the front wall of a house.

The PP-MT 30 mixture is used for cleaning heavy pollution, removingpaint from a surface, removing rust and scale, for example, cleaningmetal structures made from aluminum alloys and other nonferrous metalsfrom atmospheric and other pollution.

The PP-MT 50 mixture is used for cleaning moderate pollutions, removingpaint layer by layer, removing rust, moss, mildew, soot, graffiti fromhouse front walls, and cleaning turbine rotors and architecturalmonuments.

The PP-MT 70 mixture is used for removing light pollutions, traces ofsalt, and dirt, soil, and atmospheric pollutions.

The PP-MT 90 mixture is used for cleaning fragile surfaces from lightpollutions.

To prevent development of centers of biological destructive agents onfront walls and monuments, powdered lime that conforms to theGOST-9179-77 Standards having a grain size of up to 100 μm may be usedas a cleaning mixture.

The claimed method is performed during the operation of the apparatus asfollows:

The apparatus can operate in the cleaning, washing/waterproofing, anddrying modes. The operating modes of the sprayer are selected by openingor closing the respective valves provided on sprayer 2 and having pipesconnected thereto.

The apparatus has to be operated at an ambient air temperature of orabove +5° C.

Depending on the type and extent of pollution, the spacing between thesurface being cleaned and the outlet aperture of nozzle 24 is preferablybetween 50 and 180 mm. In operation, the nozzle axis has to be directedat an angle of 60 to 80 degrees to the house front wall being cleaned.

Operation of the apparatus comprises the successive steps of:

-   -   checking the air and suspension supply systems for gaps;    -   connecting the air supply hoses to the compressor and checking        the connection for reliability and twists of the air and        suspension supply hoses;    -   filling container 1 with a ready mixture or preparing the        mixture in container 1 itself by pouring tap water into the        container and adding the solid component of required        concentration;    -   turning on the mixture stirring mechanism for preliminary        stirring of the mixture for at least 10 seconds; and    -   turning on air and suspension flow into their respective lines        and holding sprayer 2 firmly in hand and directing nozzle 24        toward the surface being cleaned.

In the cleaning mode, air flows under a pressure of 4 to 12 atm. intoair supply device 3 where it is distributed to the respective systems.Air is dried in drier 7 of air preparation unit 6 and lubricant is addedthereto from lubricant supply device 8.

Air flows from unit 6, through a valve/controller, to air motor 5 thattransmits rotation to stirrer 4 provided with blades 9 and comminutingcutter 10 to stir the mixture of water and cleaning material orcomminute dry cleaning material of soda type in container 1.

Air also flows from unit 6 to container 1 for preparing abrasivesuspension and maintaining pressure therein at 1 to 1.5 atm. requiredfor preparing a suspension and pumping it through a hose to sprayer 2.

When the cleaning material is mixed with water in the PP-MT proportionsgiven above an abrasive suspension is produced at a pressure of 1 to 1.5atm. it requires for displaying its AHD properties and producing theRebinder effect.

The suspension is pumped from container 1 through channel 19 to pipe 20or to an annular chamber 27 to be mixed at the outlet thereof with theair stream flowing under high pressure in channel 18 from device 3 andis accelerated. From that point on, the mixture of air and suspension isaccelerated to high velocities. The stream effect produces the so-calledhydro-abrasive aerosol consisting of abrasive particles, air, andliquid. The hydro-abrasive aerosol thus produced is used to cleansurfaces. The high-velocity air stream (flowing at over 500 m/sec) isthe energy agent carrying aerosol particles in the AHD method. Aerosolparticles are water molecules gathered into drops under high pressure(about 1 atm.), with solid particles (abrasive dust) measuring between300 nm and 40 μm trapped inside them. As water strikes a surface, itreduces, due to the Rebinder effect, the strength of the surface beingcleaned, whereupon an abrasive particle destroys the dirt, and waterflushes out the broken fragments and washes them away together with theabrasive used.

The working fluid carries abrasive particles from the supply containerto the surface being treated, cleans the surface being treatedcontinuously, removes the spent abrasive particles and particles of thematerial dislodged, prevents dusting, controls the heat in the treatmentzone, and allows cleaning wastes to be collected and the working mixtureto be used again.

In the washing/waterproofing mode, air pump 14, also operated by airsupplied from device 3, forces water or waterproofing agent from washingliquid container 13 through a hose to sprayer 2.

The drying mode is turned on by closing two valves 15 on the hosesconnected to containers 1 and 13 and opening valve 15 of the hoseconnected to air supply device 3. The air stream ejected as a resultfrom sprayer 2 is used to dry a damp surface.

The claimed method used to treat a surface does not affect negativelythe original surface of metal, which is an advantage that distinguishesit from other cleaning and deactivating methods. Treatment by theclaimed method does not alter the physical and chemical composition ofthe surface layer of metal, which is a valuable factor for many types ofcomponents required to be resistant to fatigue strength deteriorationand uncontrollable chemical processes in operation. Moreover, theclaimed method helps improve the adhesive properties of metal because ofreduced water absorption by the surface thereof following treatment bythe claimed method.

1. An apparatus for aerohydrodynamic abrasive cleaning of surfacescomprising a container for preparing an abrasive suspension by astirring mechanism including a stirrer having at least one blade, and asprayer for spraying the abrasive suspension connected to said containerand a compressed gas supply device, wherein the stirrer of the stirringmechanism has a comminuting cutter provided thereon in the bottom partof the container.
 2. The apparatus as claimed in claim 1, wherein thestirring mechanism comprises an air motor associated with the stirrerand connected to the compressed air supply device through an airpreparation unit including a drier and a lubricant supply device.
 3. Theapparatus as claimed in claim 1, wherein the mixing container isprovided with a filling funnel having a locking device.
 4. The apparatusas claimed in claim 1, further having a washing liquid containerconnected to the sprayer through an air pump that is connected to thecompressed gas supply device through an air preparation unit having adrier and a lubricant supply device.
 5. The apparatus as claimed inclaim 1, wherein the units thereof are interconnected by hoses havingvalves provided thereon, the hoses connected to the sprayer beingprovided with pressure gauges.
 6. A sprayer for aerohydrodynamicabrasive cleaning of surfaces comprising a hollow body provided with anozzle at the outlet thereof, a compressed gas flow channel and acleaning suspension flow channel, both connected to the body interior,wherein the compressed air flow channel is connected to the cylindricalinterior of the body at the side thereof opposite to the nozzle, thesprayer is provided with an atomizer in the form of a T pipe received inthe body interior, the crosspiece of said T pipe extending along thebody axis and the vertical leg thereof being connected to the cleaningsuspension flow channel, the nozzle has a tapering part and acylindrical part at the outlet thereof, and the outlet aperture of theatomizer is spaced from the inlet of the cylindrical part of the nozzleto provide a zone for accelerating cleaning suspension aerosolparticles.
 7. A method for aerohydrodynamic abrasive cleaning ofsurfaces by entraining the abrasive suspension flow in compressed gas toproduce aerosol particles and directing the stream of aerosol particlesfrom the sprayer nozzle at the surface, wherein the aerosol particlesformed are accelerated within the sprayer before they are ejected fromthe nozzle.
 8. The method as claimed in claim 7, wherein the nozzle hasa part that does not flare at the outlet thereof.
 9. The method asclaimed in claim 7, wherein the abrasive suspension comprises solidparticles of loam and silica and water, wherein the loam and silica areused in the following proportions, in mass %: loam 25 to 90 silica 10 to75.
 10. The method as claimed in claim 9, wherein the solid loam andsilica particles have a size of 100 μm to 1.8 mm.